Almost always yes, and the regional differences are frequently the best part of a country's food culture. The pattern repeats worldwide: coastal regions do seafood and lighter, fresher preparations; mountain and inland areas lean on preserved meats, cheeses, and hearty stews; river deltas and agricultural heartlands have their own rice, grain, or produce specialities; and old trading cities carry outside influences you will not taste elsewhere in the country.
Even the national dish usually has fierce regional variations, with two cities each convinced theirs is the only correct version, and trying both sides of such rivalries is a delicious way to structure a trip.
To find the real regional stuff, look for restaurants that name a region in their signage, ask locals what their hometown is famous for (everyone has an instant, passionate answer), and visit regional food markets. If you travel domestically, make a point of eating the local speciality in its home region rather than the capital's imitation; the difference is usually obvious from the first bite.